1. Technical Field
The present disclosure relates to coating compositions and processes and, more particularly, to compositions for layered double hydroxide coating and sol-gel coating and related processes.
2. Related Art
High strength alloys such as aluminum alloys are widely used in various industries such as the aerospace industry due to their high strength to weight ratio. However these alloys are prone to corrosion due to the presence of alloying materials.
In order to protect these alloys from the environment, a chrome based coating may be provided on a surface of an alloy followed by application of primer and a top coat. Although organic paint systems applied on the surface provide good barrier properties against corrosion, even small defects formed in the organic paint ensure pathways for the ingress of electrolyte to the metallic surface, which initiates localized corrosion. Therefore, chromium has been used in anti-corrosion pretreatments before application of organic coatings. However, hexavalent chromium compounds have harmful effects.
Thus, there is a need for coating compositions and processes that are chromium-free and provide a coating that is corrosion-resistant.